Objective To understand the schedule and effectiveness of water-improving defluoridation projects comprehensively in control of fluorosis in drinking-water-borne endemic fluorosis areas in Shaanxi Province,and to provide a scientific basis for making strategies in prevention and control the disease for the next step.Methods The progress of drinking-water-borne endemic fluorosis water-improving defluoridation projects and operation condition were investigated in Shaanxi (fluoride content of drinking water was greater than 1.2 mg/L in the endemic areas) in 2014,and children aged 8 to 12 in 32 epidemic villages of six counties including Jingbian,Dingbian,Dali,Jingyang,Qian and Liquan were selected to survey dental fluorosis.Results In Shaanxi Province,the number of villages with water fluorine content of more than 1.2 mg/L was 5 005 and water improvement rate was 83.42％ (4 175/5 005),water-improving projects operated normally rate was 85.05％ (3 551/4 175),and scraped was 37,accounted for 0.89％ (37/4 175).There were 830 epidemic villages without water-improving projects in Shaanxi Province,and high fluoride exposed population was 579 400,mainly distributed in Yulin,Xianyang,Weinan and Yan'an cities.A total of 1 849 children aged 8 to 12 in the 6 counties were examined,the detection rate of dental fluorosis was 56.57％ (1 046/1 849),the index of dental fluorosis was 1.11.Conclusion In drinking-water-borne fluorosis epidemic areas of Shaanxi,the improved-water rate is generally high,and the normal operation of waterimproving projects is overall good,but the measures for water-improving defluoridation must be reinforced and improved.

Objective To investigate the usage of defluoridation stove and the formation of related behavior in the disease affected areas and the current situation of coal-burning-borne endemic fluorosis,to evaluate the control effect,so as to provide a theoretical basis for superior department to adjust the control strategy in time.Methods According to The Implementation Plan for Prevention and Treatment of Coal-burning-borne Endemic Fluorosis in Shaanxi Province,Ziyang and Langao in Ankang City were chosen for epidemiological survey.Using stratified sampling method,according to the degree of disease situation,each county was divided into 3 layers and then 5％ from each layer was extracted to carry out an investigation,respectively.The number of investigated village was at least 1,up to 30.The number in a non-endemic area was 1-3.Questionnaire survey of all residents was carried out to ask of the changes of cooking and heating fuel;the correct usage of the improved stove;the changes of life behavior related to the corn and pepper for human consumption and the development of prevention and treatment of post management.In endemic areas and in non-endemic areas,according to the Determination of Fluoride in Foods (GB/T 5009.18-2003),fluoride levels of corn (or rice) and chili which collected from 10 families were determined.Meanwhile,the criteria for Diagnosis of Dental Fluorosis (WS/T 208-2011) was used to diagnose dental fluorosis and the criteria of Urine-determination of Fluoride-ion Specific Electrode Method (WS/T 89-1996) was used to evaluate urine fluoride;dental fluorosis of every child aged 8-12 was examined and 10 copies of urine samples were randomly collected in each age group.Housewives and students over the age of 16 in endemic areas were quizzed of the knowledge of health and diagnosed serious skeletal fluorosis according to The Diagnostic Criteria of Endemic Fluorosis (WS 192-2008).Results The rates of correct usage of improved furnace and oven were 91.43％ (3 019/3 302) and 95.72％ (3 578/3 738).The autonomous maintenance rate of stoves was 0.61％ (49/7 998).In endemic areas,the correct drying rate and the correct storage rate of corn and pepper were all 100.0％ (300/300);the washing rate of corn and pepper before eating was 98.3％ (7 863/7 998).The fluoride median contents of corn and pepper was 0.800 and 2.863 mg/kg,respectively.In non-endemic areas,The fluoride median contents of corn and pepper was 0.443 and 4.065 mg/kg,respectively.The awareness rates of health knowledge were 81.27％ in housewives and 90.32％ in students.Dental fluorosis detection rate of 8-12 years old children was 12.52％ (87/695);the fluoride content was between 0.04-7.00 mg/L and the geometric mean value of fluoride content was 0.61 mg/L in endemic areas.There was no new case of serious skeletal fluorosis.Conclusions The prevention effect is obvious.Disease surveillance,health education and management of defluoridation stoves are keys to prevent coal-burning-borne endemic fluorosis.

Objective:To learn about the changes of the condition of coal-burning-borne endemic arsenism, the use of improved stoves and the formation of health-related behaviors in Shaanxi Province, and evaluate the effect of prevention and control measures.Methods:From 2015 to 2020, according to the "Implementation Plan for Monitoring Coal-burning-borne Endemic Arsenism in Shaanxi Province", regular field surveys were carried out in 4 natural villages, 2 counties in Ankang City and Hanzhong City, Shaanxi Province, to learn about the basic prevention and control situation in the monitoring village. Using the simple random sampling method, 10 families in each village were selected to investigate the use of stoves and the formation of health-related behaviors, and 5 of these families were selected to collect coal samples for arsenic content determination in accordance with the "Determination of Arsenic in Coal" (GB/T 3058-2008). According to the "Diagnosis of Endemic Arsenicosis" (WS/T 211-2015), the condition of the people exposed to high arsenic coal in the monitoring village was investigated. Urine samples of 30 adult patients (half males and half females) with arsenic poisoning were collected, the content of arsenic in urine was determined by the "Urine-Determination of Arsenic-Silver Diethyldithiocarbamate-Triethanolamine-Spectrophotometric Method" (WS/T 28-1996).Results:A total of 240 households were monitored in the past 6 years, and the quality conformance and correct utilization rates of improved stoves in the households monitored in the disease areas remained at 100.00% in 2018 - 2020. The utilization rate of clean energy increased from 75.00% (30/40) in 2015 to 100.00% (40/40) in 2018 - 2020 (χ 2trend = 25.5, P < 0.001). The 73.75% (177/240) of households using a variety of clean energy. From 2018 to 2020, the correct drying, storage and pre-processing washing rates of corn and pepper continued to reach 100.00% (40/40). The arsenic content of coal ( n = 120) in the disease areas was (118.09 ± 57.91) mg/kg, ranging from 16.70 to 280.94 mg/kg. The detection rate of arsenic poisoning decreased from 6.34% (231/3 646) in 2015 to 2.90% (109/3 754) in 2020 (χ 2trend = 121.8, P < 0.001), and no skin cancer or Bowen's disease was detected. The geometric mean of arsenic content in urine ( n = 720) was 0.038 1 mg/L, ranging from 0.000 5 to 0.312 9 mg/L. Conclusions:The condition of coal-burning-borne endemic arsenism areas in Shaanxi Province has reached the national elimination standard. The quality and correct utilization rate of improved stoves and the rate of using clean energy have increased. The healthy-related behaviors the people in the endemic areas have been basically formed. The prevention and control work has achieved good results.

Objective:To learn about the operation of fluoride reduction and water improvement projects, the current situation of water fluoride level and the changing trend of fluorosis in drinking water-borne endemic fluorosis areas in Shaanxi Province, and to evaluate the effect of prevention and control measures.Methods:From March 2014 to December 2021, 15 endemic villages in drinking water-borne endemic fluorosis areas of Dali, Dingbian, Jingbian, Jingyang and Liquan counties in Shaanxi Province were selected as monitoring villages to investigate the operation of water improvement projects. Water samples were collected, and the water fluoride level was detected according to the "Standard Examination Methods for Drinking Water - Nonmetal Parameters" (GB/T 5750.5-2006). "Diagnosis of Dental Fluorosis" (WS/T 208-2011) was done to detect dental fluorosis in all children aged 8 - 12 who were born and lived in the monitoring village. Using "Diagnostic Standard for Endemic Skeletal Fluorosis" (WS/T 192-2008) and "Determination of Fluoride in Urine - Ion Selective Electrode Method" (WS/T 89-2015), X-ray examination and urine fluoride level test were performed on adults over 25 years old who had lived in the monitoring village for more than 5 years, respectively.Results:From 2014 to 2021, a total of 122 water improvement projects were investigated, all of which were in normal operation. The qualified rate of water fluoride increased from 81.25% (13/16) in 2014 to 100.00% (11/11) in 2021. A total of 5 595 children aged 8 - 12 were examined, 1 790 children with dental fluorosis were detected, with a detection rate of 31.99%. The detection rate of dental fluorosis in children decreased from 52.05% (304/584) in 2014 to 9.68% (93/961) in 2021, showing an overall downward trend (χ 2trend = 533.76, P < 0.001). In 2014, 791 adults were examined, and 256 patients with skeletal fluorosis were detected, the detection rate was 32.36%. In 2019, 770 adults were examined, and 88 patients with skeletal fluorosis were detected, with a detection rate of 11.43%. The detection rate of skeletal fluorosis in adults in 2019 was lower than that in 2014, and the difference was statistically significant (χ 2 = 99.54, P < 0.001). In 2014, 754 adult urine samples were collected, and the geometric mean of urine fluoride was 2.571 mg/L. In 2019, 770 adult urine samples were collected, and the geometric mean of urine fluoride was 1.292 mg/L. The geometric mean of urine fluoride in adults in 2019 was lower than that in 2014, and the difference was statistically significant ( Z = - 12.74, P < 0.001). Conclusions:From 2014 to 2021, the water improvement projects in drinking water-borne endemic fluorosis areas in Shaanxi Province are running normally, and the qualified rate of water fluoride has increased. The incidence of dental fluorosis in children and skeletal fluorosis in adults has decreased. In the later stage, it is necessary to continuously strengthen the monitoring and management of water improvement projects to prevent the rebound of water fluoride from causing residents' illness.